The invention relates to a valve member for co-operating with an annular seat, the valve member comprising an annular plate presenting shaped portions defining an annular channel, and an annular gasket received in part in the channel and adapted to come into leaktight contact against the seat when the valve member is in the closed position. The invention also relates to a method of manufacturing such a member.
Valves of this type are known, in particular from Document JP A 61 59070, in which the plate has a thin wall of smaller height than the gasket bordering the outside of the annular channel, and the region of said thin wall close to its free end surface is bent towards the inside of the annular channel in such a manner that the inside edge between said region and the end surface compresses and/or penetrates into the gasket material, thereby clamping the gasket between said edge and the walls of the channel in the plate in such a manner as to cause the gasket to be crimped within the channel.
That technique suffers from the drawback of weakening the gasket along its circumference where it is compressed by the edge between the free end surface of the thin wall of the plate and the region close to said end surface, since even if this edge does not initially penetrate into the gasket material, repeated impacts of the gasket against its seat and aging of the gasket material will lead to such penetration taking place, thereby starting a tear along said circumference which can lead to the gasket being destroyed.
An object of the invention is to remedy that drawback in a valve member that is to co-operate with an annular seat, the valve member comprising an annular plate presenting shaped portions defining an annular channel, and an annular gasket partially received in said channel and adapted to come into leaktight contact against the seat when the valve is in the closed position, the valve member and the gasket being crimped together by an edge of a wall of the plate bordering the annular channel in which the gasket is partially received compressing and/or penetrating into the material of the gasket.
For this purpose, the invention provides a valve member adapted to co-operate with an annular seat, the valve member comprising an annular plate constituted by sheet metal having bent portions defining an annular channel, and an annular gasket received in part in the channel, said sheet metal extending about a central axis from a first end surface in the form of an inner wall forming a neck suitable for engaging on a moving valve element to another end surface at which an outer wall terminates, said outer wall bordering the annular channel and converging going towards said other end surface so as to slope towards the central axis, wherein the gasket is a gasket molded out of synthetic material presenting an outer surface which, in the absence of any stress acting thereon, comprises a region extending away from the bottom web of the channel towards the central axis in sloping manner and itself extended by a region extending away from the central axis in sloping manner, and wherein the outer wall of the plate fits snugly around at least a portion of said region extending towards the central axis of the sealing gasket without penetrating into the material of the gasket and without exerting any stress or compression thereon.
By means of this structure, the cost of manufacturing the valve member remains very low and the reliability of the gasket is significantly increased.
The valve member may also present one or more of the following characteristics:
the gasket has a base surface connected to the outer surface via a rounded zone, and the plate comprises cylindrical or approximately cylindrical segments and connecting annuluses comprising, from the first end surface: a segment constituting the inner wall of the plate; a segment extending in the opposite direction to the inner wall of the plate to constitute the inner wall of the channel; and a annulus extending outwards from the segment constituting the inner wall of the channel to constitute the bottom web of the channel, the outer wall of the channel being connected to the annulus via a fillet fitting snugly around the shape of said rounded zone of the gasket;
the plate comprises, starting from the first end surface: a first approximately cylindrical segment constituting the inner wall of the plate, forming a neck; and a first circular shoulder annulus extending outwards from the first segment in a plane perpendicular to the central axis to connect it to a second cylindrical segment extending in the same direction as the first segment, the connections between the segments and the annulus being provided via fillets;
practically the entire surface area of said other end surface of the plate fits snugly to the shape of a portion of a region of the outer surface of the gasket, which region slopes away from the central axis, and said end surface exerts no stress on said outer surface;
the gasket has a region extending towards the central axis in sloping manner and connected to a free end surface of the gasket remote from its base surface in contact with a annulus of the plate, said region extending frustoconically in the absence of any stress being exerted on the outer surface of the gasket; and
the region extending away from the bottom web of the channel towards the central axis in sloping manner comprises at least one frustoconical portion whose angle at the apex of the truncated cone, in the absence of any stress being exerted thereon, is equal to about 60xc2x0.
The invention also provides a method of manufacturing a valve member, wherein a sheet metal plate having an annular channel bordered by an approximately cylindrical outer wall has placed therein a gasket molded out of synthetic material and presenting an outer surface which, in the absence of any stress being exerted thereon, includes a region extending away from the bottom web of the channel towards the central axis in sloping manner, which region is extended by a region extending away from the central axis in sloping manner, the outer wall being crimped onto the region extending towards the central axis in sloping manner by being folded progressively inwards, and the folding of the outer wall is stopped when it fits snugly to the shape of the region extending towards the central axis in sloping manner, prior to exerting any stress on said region.
By means of this method, it is possible to obtain great precision while deforming the outer wall of the annular channel, and thus to avoid this outer wall compressing the gasket.
The method can also present the following characteristic:
to fold the outer wall towards the region extending towards the central axis in sloping manner, the outer wall is crimped onto said region by turning.